Please use this identifier to cite or link to this item: http://hdl.handle.net/10603/17801
Title: A comparative study of phenotypic and genotypic characters of environmental and clinical isolates of cryptococcus Spp.
Researcher: Dhillon, Harjeet
Guide(s): Sharma, D R
Keywords: Basidiospores
Cryptococcus
Genotype
HIV
Microbiology
Phenotype
Upload Date: 16-Apr-2014
University: Shoolini University of Biotechnology and Management Sciences
Completed Date: 12/02/2014
Abstract: With the onset of the HIV epidemic, human infections resulting from environmental exposure to the basidiomycetous yeast Cryptococcus increased significantly. Medical importance of Cryptococcus increased as a consequence of the AIDS epidemic. Cryptococcal infection is believed to be acquired by inhalation of airborne basidiospores from environmental sources which get deposited in the alveoli of host lungs causing infections of pulmonary, visceral or central nervous system. Decaying woods, eucalyptus trees, soil contaminated with bird excreta especially with pigeon droppings provide a favourable environment niche for the growth of Cryptococcus. The present study which involves the isolation and ecology of Cryptococcus has been carried out in Solan, Himachal Pradesh (India) to determine the presence of the yeast in this region from different environmental sources i.e. debris, soil and tree bark as well as pigeon droppings. The selected isolates were preliminary analyzed by using biochemical tests to identify members of Cryptococcus species complex. Then, the identity of the isolates was confirmed using microscopical and further biochemical tests. To know the species level of the isolates, in silico analysis of the large ribosomal subunit (LSU) of 28S rDNA and internal transcribed spacer (ITS) was done. Genetic differences between the isolates were studied by phylogenetic analysis. Phenotypic switching, extracellular enzymes, viz., protease, phospholipase, DNase, hemolysins and a variety of pigments were observed for ATCC, clinical and environmental strains. Ability of Cryptococcus to produce these extracellular enzymes and phenotypic switching may be associated with its virulence. All the strains had shown a variety of color hues. Such a variety of pigmentation exhibited by different species of Cryptococcus may be a possible virulence weapon of the organismand#8223;s pathogenic nature. The detection of resistant strains of C. neoformans, C. albidus, C. terreus, C. laurentii, C. luteolus and C. terrestris to amphotericin B is a sign of emerging resistance among the strains towards the standard antifungal drugs. To the best of our knowledge; the findings present in this research correspond to the first report ever on the isolation of C. flavescens from cactus in Solan. In India, C. albidosimilis and C. terrestris are reported for the first time from this region. Also, this research corresponded to the first epidemiological study of the Cryptococcus species complex in Himachal Pradesh.
Pagination: 260p.
URI: http://hdl.handle.net/10603/17801
Appears in Departments:Faculty Of Biotechnology

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5_acknowledgement.pdf43.6 kBAdobe PDFView/Open
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7_list of tables.pdf226.77 kBAdobe PDFView/Open
8_list of figures.pdf177.3 kBAdobe PDFView/Open
9_list of symbols and abbreviations.pdf279.73 kBAdobe PDFView/Open
10_chapter 1.pdfAttached File259.36 kBAdobe PDFView/Open
11_chapter 2.pdf713.7 kBAdobe PDFView/Open
12_chapter 3.pdf920.42 kBAdobe PDFView/Open
13_chapter 4.pdf14.16 MBAdobe PDFView/Open
14_chapter 5.pdf367.23 kBAdobe PDFView/Open
15_chapter 6.pdf194.05 kBAdobe PDFView/Open
16_bibliography.pdf293.6 kBAdobe PDFView/Open
17_annexure.pdf353.7 kBAdobe PDFView/Open
18_appendices.pdf442.65 kBAdobe PDFView/Open


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